The Star reported that Pistorious’s interest in guns also indicates his aggressive tendencies.

Criminologist Anna van der Hoven said that a combination of factors could have resulted in the violent crime.

Van Der Hoven feels that something must have triggered Pistorius to shoot Steenkamp. The 26-year-old Pistorious has shown signs of violence in the past.

“Abusive men suffer from pathological jealousy of their partners,” said Van der Hoven. “I haven’t diagnosed him but he also shows signs of someone with a narcissistic personality disorder.

“These kinds of individuals have a grandiose sense of self-importance However, their self-esteem is very fragile and when this is threatened, they can become violent,” she said. “They don’t know how to show sympathy for other people.”

Quoting Gareth Newham, head of crime and justice programme at the Institute of Security Studies, the daily revealed that according to statistics, 80 percent of victims of murder were known to their perpetrators.

“Twenty percent of the perpetrators are direct relatives,” Newham was quoted as saying by the daily.

Though murder rates in South Africa have fallen by 54 percent since 1994, it is still higher than the global average.